Research papers

Consumer Perceptions of Price, Quality, and Value: A Means-End Model and Synthesis of Evidence

Valarie A. Zeithaml

Evidence from past research and insights from an exploratory investigation are combined in a conceptual model that defines and relates price, perceived quality, and perceived value. Propositions about the concepts and their relationships are presented, then supported with evidence from the literature. Discussion centers on directions for research and implications for managing price, quality, and value.

Consumer Perceptions of Price, Quality, and Value: A Means-End Model and Synthesis of Evidence

Valarie A. Zeithaml

Evidence from past research and insights from an exploratory investigation are combined in a conceptual model that defines and relates price, perceived quality, and perceived value. Propositions about the concepts and their relationships are presented, then supported with evidence from the literature. Discussion centers on directions for research and implications for managing price, quality, and value.

Social Learning Theory and the Health Belief Model

Irwin M. Rosenstock, Victor J. Strecher, Marshall H. Becker

The Health Belief Model, social learning theory (recently relabelled social cognitive theory), self-efficacy, and locus of control have all been applied with varying success to problems of explaining, predicting, and influencing behavior. Yet, there is conceptual confusion among researchers and practitioners about the interrelationships of these theories and variables. This article attempts to show how these explanatory factors may be related, and in so doing, posits a revised explanatory model which incorporates self-efficacy into the Health Belief Model. Specifically, self-efficacy is proposed as a separate independent variable along with the traditional health belief variables of perceived susceptibility, severity, benefits, and barriers. Incentive to behave (health motivation) is also a component of the model. Locus of control is not included explicitly because it is believed to be incorporated within other elements of the model. It is predicted that the new formulation will more fully account for health-related behavior than did earlier formulations, and will suggest more effective behavioral interventions than have hitherto been available to health educators.

Escherichia coli and Salmonella typhimurium: Cellular and molecular biology

Philippe Lejeune

The Social Structure and Reproductive Biology of Colonies of the Mole-Rat, Cryptomys damarensis (Rodentia, Bathyergidae)

Nigel C. Bennett, J. U. M. Jarvis

Cryptomys damarensis occurs in semiarid regions of southwestern and central Africa. It lives in colonies in which reproduction is restricted to one or two of the largest-sized males and the largest female in the colony. Some division of labor, into frequent and infrequent workers, occurs within the remaining colony members. Reproduction and details of colony size and the number of breeding animals in a colony are described for two complete and five incomplete wild-captured colonies; one of the complete colonies and mole-rats from the incomplete colonies were maintained in captivity for more than 2 years. The breeding female initiated precopulatory behavior, mating occurred for about 2 weeks, the gestation length was 78–92 days, mean litter size was 2.8 (n = 10), and a maximum of four pups was born. The pups were precocial, wandered out of the nest within 24 h after birth, began to eat solids when 6 days old, and were fully weaned when 3 weeks old. When 6 weeks old, pups began to spar with each other and with some colony members, but levels of aggression were never high and the pups were incorporated into the colony. In the colony, subordinate and frequent-worker mole-rats weighed less than dominant animals and infrequent workers; mass, therefore, was not necessarily indicative of the age of the animal. During the 2-year study period, three mole-rats that were frequent workers on capture changed their castes to infrequent workers, two of them showed a concomitant increase in body mass. The colony structure and reproduction of C. damarensis are compared with those of the eusocial Heterocephalus glaber.

Empirical Model Building and Response Surfaces

Anne E. Freeny, George E. P. Box, Norman R. Draper

Introduction to Response Surface Methodology. The Use of Graduating Functions. Least Squares for Response Surface Work. Factorial Designs at Two Levels. Blocking and Fractionating 2 k Factorial Designs. The Use of Steepest Ascent to Achieve System Improvement. Fitting Second--Order Models. Adequacy of Estimation and the Use of Transformation. Exploration of Maxima and Ridge Systems with Second--Order Response Surfaces. Occurrence and Elucidation of Ridge Systems, I. Occurrence and Elucidation of Ridge Systems, II. Links Between Emprirical and Theoretical Models. Design Aspects of Variance, Bias, and Lack of Fit. Variance----Optimal Designs. Practical Choice of a Response Surface Design. Subject Index. Index.

Structural equation modeling in practice: A review and recommended two-step approach.

James C. Anderson, David W. Gerbing

In this article, we provide guidance for substantive researchers on the use of structural equation modeling in practice for theory testing and development. We present a comprehensive, two-step modeling approach that employs a series of nested models and sequential chi-square difference tests. We discuss the comparative advantages of this approach over a one-step approach. Considerations in specification, assessment of fit, and respecification of measurement models using confirmatory factor analysis are reviewed. As background to the two-step approach, the distinction between exploratory and confirmatory analysis, the distinction between complementary approaches for theory testing versus predictive application, and some developments in estimation methods also are discussed.

Current protocols in molecular biology

Tom Sargent

Apolipoprotein E: Cholesterol Transport Protein with Expanding Role in Cell Biology

Robert W. Mahley

Apolipoprotein E is a plasma protein that serves as a ligand for low density lipoprotein receptors and, through its interaction with these receptors, participates in the transport of cholesterol and other lipids among various cells of the body. A mutant form of apolipoprotein E that is defective in binding to low density lipoprotein receptors is associated with familial type III hyperlipoproteinemia, a genetic disorder characterized by elevated plasma cholesterol levels and accelerated coronary artery disease. Apolipoprotein E is synthesized in various organs, including liver, brain, spleen, and kidney, and is present in high concentrations in interstitial fluid, where it appears to participate in cholesterol redistribution from cells with excess cholesterol to those requiring cholesterol. Apolipo-protein E also appears to be involved in the repair response to tissue injury; for example, markedly increased amounts of apolipoprotein E are found at sites of peripheral nerve injury and regeneration. Other functions of apolipoprotein E, unrelated to lipid transport, are becoming known, including immunoregulation and modulation of cell growth and differentiation.

Prospect theory: An analysis of decision under risk

Daniel Kahneman, Amos Tversky

Introduction Expected utility theory has dominated the analysis of decision making under risk. It has been generally accepted as a normative model of rational choice (Keeney and Raiffa, 1976), and widely applied as a descriptive model of economic behavior (e.g., Friedman and Savage, 1948, and Arrow, 1971). Thus, it is assumed that all reasonable people would wish to obey the axioms of the theory (von Neumann & Morgenstern, 1944, and Savage, 1954), and that most people actually do, most of the time. The present paper describes several classes of choice problems in which preferences systematically violate the axioms of expected utility theory. In the light of these observations we argue that utility theory, as it is commonly interpreted and applied, is not an adequate descriptive model and we propose an alternative account of choice under risk. Critique Decision making under risk can be viewed as a choice between prospects or gambles. A prospect ( x 1 , p 1 ; …; x n , p n ) is a contract that yields outcome x i with probability p i , where p 1 + p 2 + … + p n = 1. To simplify notation, we omit null outcomes and use ( x, p ) to denote the prospect ( x, p ; 0, 1 – p ) that yields x with probability p and 0 with probability 1 – p . The (riskless) prospect that yields x with certainty is denoted by ( x ). The present discussion is restricted to prospects with so-called objective or standard probabilities.

Physics at Surfaces

Andrew Zangwill

Physics at Surfaces is a unique graduate-level introduction to the physics and chemical physics of solid surfaces, and atoms and molecules that interact with solid surfaces. A subject of keen scientific inquiry since the last century, surface physics emerged as an independent discipline only in the late 1960s as a result of the development of ultra-high vacuum technology and high speed digital computers. With these tools, reliable experimental measurements and theoretical calculations could at last be compared. Progress in the last decade has been truly striking. This volume provides a synthesis of the entire field of surface physics from the perspective of a modern condensed matter physicist with a healthy interest in chemical physics. The exposition intertwines experiment and theory whenever possible, although there is little detailed discussion of technique. This much-needed text will be invaluable to graduate students and researchers in condensed matter physics, physical chemistry and materials science working in, or taking graduate courses in, surface science.

On the evaluation of structural equation models

Richard P. Bagozzi, Youjae Yi

Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density

Chengteh Lee, Weitao Yang, Robert G. Parr

A correlation-energy formula due to Colle and Salvetti [Theor. Chim. Acta 37, 329 (1975)], in which the correlation energy density is expressed in terms of the electron density and a Laplacian of the second-order Hartree-Fock density matrix, is restated as a formula involving the density and local kinetic-energy density. On insertion of gradient expansions for the local kinetic-energy density, density-functional formulas for the correlation energy and correlation potential are then obtained. Through numerical calculations on a number of atoms, positive ions, and molecules, of both open- and closed-shell type, it is demonstrated that these formulas, like the original Colle-Salvetti formulas, give correlation energies within a few percent.

Development and validation of brief measures of positive and negative affect: The PANAS scales.

David Watson, Lee A. Clark, Auke Tellegen

In recent studies of the structure of affect, positive and negative affect have consistently emerged as two dominant and relatively independent dimensions. A number of mood scales have been created to measure these factors; however, many existing measures are inadequate, showing low reliability or poor convergent or discriminant validity. To fill the need for reliable and valid Positive Affect and Negative Affect scales that are also brief and easy to administer, we developed two 10-item mood scales that comprise the Positive and Negative Affect Schedule (PANAS). The scales are shown to be highly internally consistent, largely uncorrelated, and stable at appropriate levels over a 2-month time period. Normative data and factorial and external evidence of convergent and discriminant validity for the scales are also presented.

Fiftieth volume of theoretical computer science

Maurice Nivat

Spatial Econometrics: Methods and Models

Luc Anselin

Snakes: Active contour models

Michael Kass, Andrew Witkin, Demetri Terzopoulos

On the Evaluation of Structural Equation Models

Richard P. Bagozzi, Youjae Yi

Cell Biology of Extracellular Matrix

Elizabeth D. Hay

At a recent meeting to discuss the domains of cell biology, I put forth a case for the extracellular matrix, even though my argument ran the risk of falling on deaf ears. After all, the matrix is EXTR

Serber Says: About Nuclear Physics – World Scientific Lecture Notes in Physics Vol 10

A.B. Clegg

Robert Serber 1987 Singapore: World Scientific vii + 298 pp price £40.85 ISBN 9971 50 1 58 9 From the late 1930s to the early 1950s a considerable effort went into understanding the broad aspects of nuclei and, in particular, nuclear forces at relatively low energies. This was a very important and necessary contribution to physics, leading to important understanding of magnitudes and to ideas like charge independence and isotopic spin.

Nursing Research: Principles and Methods

Stephen R. Marrone

Nursing Research: Principles and Methods, third ed. Denise F. Polit, Bernadette P. Hungler. J B Lippincott Co, E Washington Square, Philadelphia, PA 19105, 1987, 571 pp, $27.50 clothbound.

Pollination biology of the Proteaceae in Australia and southern Africa

Brian Collins, Tony Rebelo

Abstract Proteaceae are most diverse in southern Africa and Australia, especially in the south‐western portions of these regions. Most genera have some species in flower at all times of the year, although generally there is a preponderance of species that flower between late winter and early summer. The one genus that is an exception to this generalization is Banksia, which either has approximately the same percentage of species in flower at various times of the year (southwestern Australia) or peaks in autumn (southeastern Australia). Within particular communities, opportunities for hybridization among congeneric species are minimized by staggered flowering times, different pollen vectors and/or various incompatibility mechanisms. Birds, mammals and arthropods have been identified as visitors to the inflorescences of many Proteaceae. The most common avian visitors to the majority of genera in Australia are honeyeaters, although lorikeets, silvereyes and approximately 40 other species sometimes may be important. Sugarbirds and sunbirds are seen most frequently at inflorescences of Protea, Leucospermum and Mimetes in southern Africa, although they rarely visit other genera. In most cases, avian visitors forage in a manner that permits the acquisition and transfer of pollen. Limited evidence supports the hypothesis that birds are selective in their choice of inflorescences, responding to morphological and/or colour changes and usually visiting those inflorescences that offer the greatest nectar rewards. Arthropods may be equally selective, although it is possible that only the larger moths, bees and beetles are important pollinators, even for those plant species that rely entirely on arthropods for pollen transfer. Mammals are pollen vectors for some Proteaceae, especially those that have geoflorous and/or cryptic inflorescences. In Australia, small marsupials may be the most important mammalian pollinators, although rodents fill this niche in at least some southern African habitats. All but two genera of Proteaceae are hermaphroditic and protandrous, the exceptions being the dioecious southern African genera Aulax and Leucadendron. For hermaphroditic species, the timing of visits by animals to inflorescences is such that they not only acquire pollen from freshly opened flowers but also brush against pollen presenters and stigmas of others that have lost self‐pollen and become receptive. Birds and insects (and probably mammals) generally forage in such a way as to facilitate both outcrossing and selfing. Some species are self‐compatible, although many require outcrossing if viable seed is to be formed. Regardless of which animals are the major pollen vectors, fruit set is low relative to the number of flowers available, especially in Australian habitats. Functional andromonoecy of the majority of flowers is advanced as the major cause of poor fruit set. The pollination biology and breeding systems of Australian and southern African Proteaceae resemble one another in many ways, partly because of their common ancestry, but also due to convergence. Divergence is less obvious, apart from the dichotomy between dioecious and hermaphroditic genera, and differences in the levels of seed set for Australian and African species. Future studies should concentrate on identifying the most important pollinators for various Proteaceae, the manner in which their visits are integrated with floral development and factors responsible for limiting fruit set.

Nursing Research: Principles and Methods

Gertrude Kay McFarland, Denise F. Polit, Bernadette P. Hungler

Part I:The Scientific Research Process Introduction to Nursing Research Overview of the Research Process Research Problems, Research Questions, and Hypotheses Part II:Contexts for Nursing Research The Knowledge Context:Literature Reviews Conceptual and Theoretical Contexts The Ethical Context of Nursing Research Part III:Designs for Nursing Research Selecting a Research Design Research Design for Quantitative Studies Research Control in Quantitative Research Qualitative Research Design and Approaches Integration of Qualitative and Quantitative Designs Sampling Designs Part IV:Measurement and Data Collection Designing and Implementing a Data Collection Plan Self-Reports Observational Methods Biophysiologic and Other Data Collection Methods Assessing Data Quality Part IV:The Analysis of Research Data Quantitative Analysis:Descriptive Statistics Inferential Statistics Multivariate Statistical Procedures Designing and Implementing a Quantitative Analysis Strategy The Analysis of Qualitative Data Computers and Nursing Research Part VI:Communication in the Research Process Writing a Research Report Evaluating Research Reports Utilization of Nursing Research Writing a Research Proposal Index

Practical Issues in Structural Modeling

Peter M. Bentler, Chih-Ping Chou

Practical problems that are frequently encountered in applications of covariance structure analysis are discussed and solutions are suggested. Conceptual, statistical, and practical requirements for structural modeling are reviewed to indicate how basic assumptions might be violated. Problems associated with estimation, results, and model fit are also mentioned. Various issues in each area are raised, and possible solutions are provided to encourage more appropriate and successful applications of structural modeling.